Superstar women lead IT at some of the biggest global corporations, yet the path to the top isn't clear for the next generation.

Ursula Burns at Xerox. Ellen Kullman at DuPont. Ginni Rometty at IBM. And most famously, Marissa Mayer at Yahoo, with a baby on board and a Twitterstream in tow.

Each time a female engineer takes the helm at a prominent technology company, the industry breathes a sigh of relief and pats itself on the back. See? Self-proclaimed "girl geeks" like Mayer really can survive and thrive in IT and research.

Add to that the fact that more female CIOs than ever are leading the tech charge at Fortune 500 companies like Exxon Mobil, Boeing, Dell, Walmart, Bank of America, Xerox and GE, and it's easy to conclude that change really has come to one of the last male-dominated boxes on the corporate org chart.

Or maybe not. According to data from the U.S. Department of Labor's Bureau of Labor Statistics, in 2011 women made up 57% of the country's professional workforce but held just 25% of the jobs in professional computing occupations. And those Fortune 500 female CIOs? They still account for just 12% of the total, according to data from Boardroom Insider.

The persistently lopsided male-to-female ratios distress pioneering women like Nora Denzel, a former senior vice president at Intuit and Hewlett-Packard who graduated with a B.S. in computer science in 1984.

At the time, Denzel had no idea that the charge she was leading would wither behind her. "In the early '80s, the whole space thing was going on, PCs had just come out, the occupational projections were saying there was going to be such a shortage of talent," she recounts. "I wouldn't go as far as saying computer science was sexy, but there was that sense that the sky was the limit."

Flash forward almost 30 years to find Denzel, currently a member of the board of directors at the nonprofit Anita Borg Institute for Women and Technology, delivering the keynote address at the institute's recent 2012 Grace Hopper Celebration of Women in Computing conference in Baltimore.

The theme of her talk: "Are we there yet?" Her short answer: No.

"We were making progress until the mid '80s -- the supply of women peaked at 37% in '85. None of us knew that by 2010, only 18% of CS undergrads would be women," she laments. "The numbers moved, but in reverse. It's a revolution in reverse."

The numbers moved, but in reverse. It's a revolution in reverse.
Nora Denzel, Anita Borg Institute

Should corporations care if their IT workforce lacks women? Beyond check-the-box feel-goodism, is there any ROI in dedicating resources to cultivate, recruit, mentor and promote women in technical roles?

Absolutely, says Sophie Vandebroek, CTO at Xerox, which also has a female CEO and a female CIO. Female-friendly policies give an organization access to the full range of talent available in the marketplace. "It's hard enough finding people who meet our standards -- exceptional Ph.D.s and engineers, especially U.S. citizens," she says. "Without a diverse organization, we're not going to be able to attract the best person for the job."

In addition to her CTO role, Vandebroek is president of the Xerox Innovation Group, which oversees Xerox's research centers in Europe, Asia, Canada and the U.S., including the storied Palo Alto Research Center (PARC).

"We have no problem hiring excellent people at PARC," she says with a laugh, "but how do we convince talented engineers to move to our Rochester, N.Y., facility?" Xerox's diversity initiatives are a key recruiting tool. "Nobody wants to be the only woman, or the only Hispanic, or young person, or the one gay person. They want to see others who look and act like them in the workplace."